Elastomers (rubbers) are important commercial materials, being used in many common items. Until a couple of decades ago, most rubber was crosslinked to make it a useable material. However, once crosslinked the rubber could not be reformed, and for most practical purposes scrap or used rubber could not be reused. This problem was solved to some extent by the introduction of so-called thermoplastic elastomers (TPEs, also sometimes called elastoplastics), which are thermoplastics which can be remolded, but at their normal use temperatures act like crosslinked elastomers. Most TPEs derive their rubberlike properties because they are polymers which have elastomeric and thermoplastic segments. The elastomeric segments give the TPEs their elastomer-like properties, while the thermoplastic segments act much as chemical crosslinks do.
While TPEs with properties similar to hydrocarbon-type elastomers have been in use for many years, more highly chemically and thermally resistant TPEs have been much more difficult to obtain. This is partly because in being chemically resistant it is more difficult to assemble the various polymer segments needed for a TPE. Fluoropolymers are a well known type of polymer that are chemically and thermally resistant and are known in thermoplastic and elastomeric forms. However, there has been great difficulty in obtaining fluorinated TPEs that have properties approaching the "conventional" thermoset fluoropolymers.
U.S. Pat. No. 4,158,678 describes the preparation of certain "segmented polymers containing fluorine". These polymers are free radically prepared and involve the use of certain iodine compounds. At least some of the polymers described in this patent are said to possess "a thermoplastic rubbery property".
M. Tatemoto, Purasuchikkusu, vol. 42, No. 10 (1991), p. 71-76 describes certain fluorinated thermoplastic elastomers, made by a free radical process dependent on chain transfer to iodine atoms bound to carbon atoms. Polymers with structures disclosed herein are not described.